Three Essential Steps

A major function of the kidney is conservation of water by increasing the solute concentration in the urine. This is accomplished by the action of about a million nephrons working together with their attached collecting ducts. Although the process is much more complex than pictured here, it helps to understand the underlying concept if we break the process down into its three essential steps. It is important to realize that in reality, all three steps are going on at the same time.

To the right of the animation is a complete set of controls, so that you can focus on any part of the process that you want. Click on the "Run" button to begin. The animation will stop after each step in the explanation; click "Run" each time to continue. For a detailed explanation of the controls, click on the "Help" button.